I recently took the door panel off my 88 gt to install a new door handle and now I can't seem to get the panel back on. Any tricks or tips?

 

Hard to tell without being able to see it exactly but the place people usually get hung up is at the top of the panel where it has to overlap and fit into the window channel. Most Ford door panels of that era required that you put the door handle through the opening in the door panel first, then line up the top of the door panel to fit down into the window channel. After that all you have to do is make sure the panel clips around the perimeter of the door are lined up so that you can pop them back into the holes all the way around. Last of course you re-install extra screws that secure the panel and reattach any trim that was taken off during removal.